setInterval() Help please!

Hi,
I want to have control on my movie with setInterval(). I have three MCs in their own layers which would appear on the stage in turn.
In frame one I have a fadeIn function for MC1 which works ok.
I want that MC2 appears after 3 seconds and MC3 after 6 seconds.
Where do I put setInterval functions for MC2 and MC3? I mean which frame in their own layer?
Thanks,
mx-guest2004

Ok. Nobody answered.
I think I have to use some kind of pausing function to make a time delay for my MCs.
I found this code for pausing and put in the first frame in a seperate layer. In that first frame in another layer I call this function for one of my MCs, but it doesn’t work.
[AS]
movieclip.prototype.Pause = function(pzeit) {
var go = function(obj) {
obj.play();
clearInterval(id);
}
this.stop();
var id = setInterval(go,pzeit,this);
}
[/AS]
and call this function in same frame (another layer):
[AS]
onClipEvent (load) {
this.Pause(3000);
}
[/AS]

mx-guest2004